C5 2.2HDi gremlins

[StvC]

Hi all, recently purchased a C5 estate and inherited a few quirks as is the norm with our beloved French bargains. I've had a search and have a few ideas but thought I'd try and narrow things down a little more in a wide ranging post that google searchers would find helpful.

Gremlins are:
1.) Speedo is not working, usually just sits at 6 o clock position unless I turn off engine whilst rolling then bump it then it will register but nowhere near the correct speed and seems to lose 'grip' and eventually sag back in stages to the start position. I read here that it could be the stepper motor but the fact it registered a little I wondered if it was more 'pin' related than the whole motor. Someone linked a company somewhere which I can't find again that used to sell the motor but now just sell a clip thingy for a tenner? Is this what I need?

2.) Left air vent from centre console seems to blow hot all the time. Bit funny this one, I turn the CC down to minimum and the left vent will still blow hot air at whatever speed the fan is at, currently just shut of the centre vents but maybe just a mixer flap that needs freeing up or something perhaps?

3.) Drives A1 unless flooring it to get up a steep hill or a rapid overtake on a country road. Then you get ESR and Antipollution + service light on and loss of turbo/limp mode. I've had similar problem in other marques and normally a turn off the ignition and start again fixes it, but in this case it doesn't. Even if I stop and turn off everything for like 5-10 mins it still has the problem. If I leave it longer though, overnight, or an hour or so, it does reset back to normal and can drive fine unless I hit a very steep hill near me that requires foot to the floor pretty much. Is this looking like a DPF thing? Do I just need diag on it or could I blank something off or clean the filter? Is so where is it located/accessed.

4.) Unblock fuel filter message comes on when ambling a long no apparent change to power. Is this related to the above? Very occasionally I see a puff of blue smoke in rear view mirror but I can't replicate it on the overrun or whatever as I have done before when seeing blue smoke. The guy I bought it from said he'd changed the actual fuel filter but I understand from reading around here, it may not have anything to do with the fuel filter.

Hope you don't mind the sprawling post, will split it up if moderators prefer.

TIA Steve

[SaabC5]

Numbers 3 & 4 always meant a blocked DPF on my Mk1 2.2Hdi. You can just take it off, split in half and clean with a pressure washer and you should be good to go.
Number 2 is the control flap motor, i bet the left hand vent on passengers side only blows hot as well. There's a revised motor with a longer spline that cures the fault but it's about £80 to buy, access is via the right hand side of the glovebox once you've taken the liner out.

[StvC]

Legend...thanks mate. How do I get to the DPF?

[SaabC5]

Its underneath the car in the middle half way back. There are a couple of sensors and two silver small bore pipes that need undoing near the downpipe from the exhaust manifold. You can then undo four bolts that holds the two sections of the DPF together (they may be rusted solid, you can cut them off with an angle grinder and replace with 4 similar bolts if need be). Chuck a £6 bottle of acidic wheel cleaner into the honeycomb section and let sit for 5 minutes before blasting the crap out with a pressure washer. Allow it to drain for 20 minutes and then refit.
This is what you're looking for.